The present invention relates to fabric softeners, and more particularly to fabric softener concentrates that are added during the rinse cycle of a laundering process. Specifically, the present invention relates to a rinse cycle fabric softener concentrate that includes at least one polyquatemary (polyquat) ammonium anionic scavenger and at least one cationic quaternary ammonium fabric softener agent. The rinse cycle fabric softener concentrate of the present invention containing the polyquatemary ammonium anionic scavenger exhibits improved performance, i.e., softening, dye transfer inhibition, higher solids formulations and improved water dispersibility, as compared to prior art fabric softeners that do not contain the anionic scavenger described herein.
In the field of laundering, it is well known to add a liquid fabric softener containing at least one fabric softening agent such as a cationic quaternary ammonium compound or salt thereof directly into the laundering process. The addition of the liquid fabric softener typically occurs during the rinse cycle itself. Although some improved softness may arise from the use of prior art fabric softeners, the overall softening performance of prior art fabric softeners is hindered due to high levels of residual anionics which are typically present in the washing liquor; the high level of residual anionics in the laundry liquor is the result of utilizing detergents that contain a high concentration of anionic surfactants which are not typically removed prior to the rinsing cycle. This is particularly the case in North America where high levels of anionic surfactants are employed in the detergent, and little or no additional (single rinse cycle following wash cycle) rinsing occurs prior to the addition of the fabric softener.
The hindered softening performance of prior art fabric softeners can be attributed to the high affinity that the cationic softening agents have for negatively charged species and/or surfaces. When high levels of anionics are present in the laundering liquor, the anionics compete with the negatively charged surfaces of the laundered fabric for the cationic fabric softener agent and complexation of the anionics and the cationic fabric softener agent occurs. Complexation of the anionics with the cationic fabric softener agent is undesirable since it significantly reduces the overall amount of fabric softener agent present in the rinse cycle that is needed to obtain a high degree of softening. Thus, because of the reduced levels of fabric softener agents in the laundry liquor, prior art fabric softeners can not achieve a high degree of softness.
Attempts have been made in the prior art to increase the amount of cationically charged species present in the laundry liquor. For example, it is known to add so-called xe2x80x9ccharge boostersxe2x80x9d to fabric softeners in order to increase the amount of positively charged species present in the laundry liquor during the rinse cycle. Illustrative examples of some prior art charge boosters, which are disclosed in WO 94/20597, U.S. Pat. Nos. 5,759,990, and 5,474,690, for example, include, but are not limited to:
(i) Quaternary ammonium compounds having the formula: 
wherein R1, R2, R3 and R4 are independently C1-22 alkyl, C3-22 alkenyl, R5xe2x80x94Q(CH2)mxe2x80x94, where R5 is a C1-22 alkyl, and mixtures thereof; Q is a carbonyl unit; m is from 1 to 6, and X is an anion;
(ii) Polyvinyl amines having the formula 
wherein y is from 3 to about 5000. Optionally, one or more of the polyvinyl amine backbone xe2x80x94NH2xe2x80x94 unit hydrogens can be substituted with an alkyleneoxy moiety;
(iii) Polyalkylenimines having the formula 
wherein each R6 is independently a C2-4 alkylene, C3-8 substituted alkylene and mixtures thereof; the value of m is from 2-700 and the value of n is from 0 to 350. Optionally, one or more of the polyvinyl amine backbone xe2x80x94NH2xe2x80x94 unit hydrogens can be substituted with an alkyleneoxy moiety;
(iv) Poly-quaternary ammonium compounds having the formula: 
wherein R is substituted or unsubstituted C2-12 alkylene, substituted or unsubstituted C2-12 hydroxyalkylene; each R1 is independently C1-4 alkyl, each R2 is independently C1-22 alkyl, C3-22 alkenyl, R5xe2x80x94Qxe2x80x94(CH2)mxe2x80x94, where R5 is C1-22 alkyl, C3-22 alkenyl, and mixtures thereof; m is from 1 to 6; Q is a carbonyl unit; and X is an anion; and
(v) Cationic polymers such as amine salts or quaternary ammonium salts.
U.S. Pat. No. 6,083,899 to Baker, et al. (and the corresponding International Application WO 98/12292) provide a fabric softener composition that has enhanced softening benefits which comprises at least one fabric softener active and at least one cationic charge booster. The charge boosters disclosed in the Baker, et al. patent have structural formulas that are similar to charge boosters (i)-(iv) described above. In accordance with the disclosure of Baker, et al., the charge boosters reportedly increase the performance of cationic fabric softener actives that have diminished or insufficient charge density to a level which allows the low charge density surface active agent to be used in fabric softening formulations. Moreover, the Baker, et al. patent indicates that the cationic charge boosters have the effect of increasing the net cationic charge concentration independent of the intrinsic properties of the softening active.
Although prior art charge boosters are known, there is still a need for developing new and improved charge boosters (hereinafter referred to as xe2x80x9canionic scavengersxe2x80x9d) that serve to further increase the level of cationic active agent present in the rinse cycle of a laundering process. Moreover, prior art fabric softener formulations that include the above mentioned charge boosters typically require a separate polymeric dye transfer inhibition agent that prevents dye transfer during laundering. The addition of a separate dye transfer agent increases the number of processing steps in formulating the fabric softener. The additional processing steps result in an increased cost in producing the fabric softener which is passed along to the consumer.
In view of the above mentioned drawbacks with prior art rinse cycle fabric softeners, it would be extremely beneficial if a new and improved rinse cycle fabric softener concentrate was developed that was capable of providing improved softness as well as inhibiting dye transfer, without the need of adding separate ingredients to accomplish the aforementioned properties.
The present invention provides a rinse cycle fabric softener concentrate that has improved fabric softening capabilities, while being capable of inhibiting dye transfer without the need of utilizing separate ingredients which carry out the aforesaid functions. Specifically, the rinse cycle fabric softener concentrate of the present invention is a blend of quaternary ammonium compounds that consists essentially of:
(i) from about 3 to about 40 weight % of at least one polyquat selected from the group consisting of:
(a) a quat having structural formula (I): 
where R1 is a C10-24 alkyl, an ester having the formula R1C(O)ORxe2x80x94 where R1 is defined above and R is a substituted or unsubstituted C1-6 alkylene, or an amide having the formula R1C(O)NRxe2x80x94 where R1 and R are as defined above; each R2 independently is a xe2x80x94(AO)1-6H group where A is a C2-4 straight chained or branched alkyl; each R3 independently is a C1-6 alkyl; Y is from 1 to 6 and A is an anion,
(b) a quat having structural formula (II): 
wherein R1 is a C10-24 alkyl, an ester having the formula R1C(O)ORxe2x80x94 where R1 is defined above and R is a substituted or unsubstituted C1-6 alkylene, or an amide of the formula R1C(O)NRxe2x80x94 where R1 and R are as defined above; each R4 independently is a C1-6 alkyl, or a xe2x80x94(AO)1-6H group where A is a C2-4 straight chained or branched alkyl; each R5 independently is a C1-6 alkyl; Y is from 1 to 6; x is from 1 to 5; n is the number of moles of monovalent anion Axe2x88x92 to provide a net zero charge; and A is a monovalent anion, and
(c) a combination of quats having structural formulas (I) and (II); and
(ii) from about 60 to about 97 weight % of a cationic fabric softener agent selected from ester-containing quaternary ammonium compounds (i.e., ester quats), amido amine quaternary ammonium compounds, imidazoline quats and mixtures and salts thereof.
The rinse cycle fabric softener concentrate of the present invention is an emulsion, i.e., it is not clear. Moreover, the inventive concentrate may be further characterized as being a waxy mixture of the aforementioned components. In some embodiments, the inventive concentrate may be used with one or more conventional liquid carriers such as water, C1-4 monohydric alcohols, C2-10 polyhydric glycols, diols or triols, polyalkenylene glycols, and mixtures thereof to form a liquid rinse cycle fabric softener formulation. In this embodiment of the present invention, the concentration of the inventive rinse cycle fabric softener concentrate in the liquid fabric softener formulation is from about 2 to about 40 weight %.
In a further embodiment of the present invention, a concentrate or formulation containing up to 60 weight % active ingredient is also contemplated.
The rinse cycle fabric softener concentrate or liquid fabric softener formulation of the present invention is used in the rinse cycle of any laundering process where conventional detergents are employed. In one embodiment of the present invention, the inventive concentrate or formulation is used in a laundering liquor where the detergent contains a high level of anionic surfactants. The term xe2x80x9chigh level of anionicsxe2x80x9d refers to a detergent composition that contains at least 10% or more of an anionic surfactant. The rinse cycle fabric softener formulation of the present invention is used in an amount of from about 0.05 to about 0.4 grams of said fabric softener actives per 100 grams of fabric to be laundered.
The improved softness that is obtainable using the rinse cycle fabric softener concentrate or formulation of the present invention is attributed to one of the above-mentioned polyquat compounds. Specifically, the polyquat compounds of the present invention serve as an efficient anionic scavenger which inhibits complexation of the anionics with the softening agents.
In addition to improved softness, the inventive rinse cycle fabric softener concentrate or formulation is also effective in preventing dye transfer. Moreover, the presence of the polyquat compounds in the fabric softener unexpectedly increases the water dispersibility of the active agents present in the fabric softener. The increased water dispersibility results in a higher solids rinse cycle fabric softener formulation that contains up to at least 25% of softening actives. More preferably, the rinse cycle fabric softener formulation of the present invention contains from about 2 to about 40% of softening actives.